Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / UIAutomation / UIAutomationClient / MS / Internal / Automation / WinEventWrap.cs / 1305600 / WinEventWrap.cs
//---------------------------------------------------------------------------- // //// Copyright (C) Microsoft Corporation. All rights reserved. // // // // Description: Lightweight class to wrap Win32 WinEvents. // // History: // 06/17/2003 : BrendanM Ported to WCP // //--------------------------------------------------------------------------- // PRESHARP: In order to avoid generating warnings about unkown message numbers and unknown pragmas. #pragma warning disable 1634, 1691 using System; using System.Security; using System.Collections; using System.Runtime.InteropServices; using System.ComponentModel; using System.Diagnostics; using MS.Win32; namespace MS.Internal.Automation { // Lightweight class to wrap Win32 WinEvents. Users of this class would // inherit from WinEventWrap do the following: // 1. Call the base constructor with a params array of event identifiers // 2. Override WinEventProc to provide an implementation. internal class WinEventWrap { //----------------------------------------------------- // // Constructors // //----------------------------------------------------- #region Constructors // ctor that takes an array of events internal WinEventWrap(int [] eventIds) { Debug.Assert(eventIds != null && eventIds.Length > 0, "eventIds is invalid"); _eventIds = (int [])eventIds.Clone(); _hHooks = new IntPtr[_eventIds.Length]; Init(); } ~WinEventWrap() { Clear(); } #endregion Constructors //------------------------------------------------------ // // Internal Methods // //----------------------------------------------------- #region Internal Methods internal virtual void WinEventProc(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime) { // override this to provide an implementation } internal void Clear() { StopListening(); lock(this) { _clientCallbacks.Clear (); } if (_gchThis.IsAllocated) { _gchThis.Free(); } } internal void AddCallback(object clientCallback) { lock (this) { _clientCallbacks.Add(clientCallback); } } internal bool RemoveCallback(object clientCallback) { if (clientCallback == null) return true; // temp until cleanup of WinEvent code is complete bool listIsEmpty = true; lock (this) { if (_clientCallbacks.Count == 0) return true; // remove a specific callback _clientCallbacks.Remove(clientCallback); listIsEmpty = (_clientCallbacks.Count == 0); } return listIsEmpty; } // install WinEvent hook and start getting the callback. ////// Critical - as this calls SetWinEventHook which has a SUC on it and also calls /// the setter for _hHook. /// Safe - as this does not allow an arbitrary method to be set up as a hook and /// also doesn't allow an aribtrary value to be set on _hHook.Value. /// internal void StartListening() { _fBusy = true; int i = 0; foreach (int eventId in _eventIds) { // There is no indication in the Windows SDK documentation that SetWinEventHook() // will set an error to be retrieved with GetLastError, so set the pragma to ignore // the PERSHARP warning. #pragma warning suppress 6523 _hHooks[i] = UnsafeNativeMethods.SetWinEventHook(eventId, eventId, IntPtr.Zero, _winEventProc, 0, 0, _fFlags); if (_hHooks[i] == IntPtr.Zero) { StopListening(); throw new Win32Exception(); } i++; } _fBusy = false; } internal void StopListening() { // ASSUMPTION: Before StopListening is called, all callback delegates have been removed // so that any events received while hooks are being removed become noops (since there's // no handlers for them to call). _fBusy = true; for (int i=0;i<_hHooks.Length;i++) { if (_hHooks[i] != IntPtr.Zero) { // There is no indication in the Windows SDK documentation that UnhookWinEvent() // will set an error to be retrieved with GetLastError, so set the pragma to ignore // the PERSHARP warning. #pragma warning suppress 6523 UnsafeNativeMethods.UnhookWinEvent(_hHooks[i]); _hHooks[i] = IntPtr.Zero; } } if (_qEvents != null) { _qEvents.Clear(); } _fBusy = false; } // Handlers may make a call to another process so don't want to lock around code that protects _clientCallbacks. // Instead, grab the callbacks w/in a lock then call them outside of the lock. This technique has potential for // error if (for instance) handler A could remove both itself and handler B but for now don't need to worry // about handlers getting out of [....] with the ones in the master array because the callbacks are defined w/in // this code and the handler for new UI doesn't remove itself (or anyone else). internal object[] GetHandlers() { lock (this) { object[] handlers = new object[_clientCallbacks.Count]; for (int i = 0; i < _clientCallbacks.Count; i++) handlers[i] = _clientCallbacks[i]; return handlers; } } #endregion Internal Methods //------------------------------------------------------ // // Private Methods // //------------------------------------------------------ #region Private Methods // queue winevents so that the get processed in the order we receive them. If we just // dispatch them as we get them, we'll end up getting some _while_ we are processing others, // and end up completing those events out of order, making the event order appear backwards. // This code checks whether we are currently processing an event, and if so, queues it so that // we process it when we're done with the current event. private void WinEventReentrancyFilter(int winEventHook, int eventId, IntPtr hwnd, int idObject, int idChild, int eventThread, uint eventTime) { if ( _fBusy ) { _qEvents.Enqueue(new WinEvent(eventId, hwnd, idObject, idChild, eventTime)); } else { _fBusy = true; try { PreWinEventProc(eventId, hwnd, idObject, idChild, eventTime); // deliver this event } catch( Exception e ) { if( Misc.IsCriticalException( e ) ) throw; // ignore exceptions for now since we've no way to let clients add exception handlers } while (_qEvents.Count > 0) { WinEvent e = (WinEvent)_qEvents.Dequeue(); // process queued events try { PreWinEventProc(e._eventId, e._hwnd, e._idObject, e._idChild, e._eventTime); } catch( Exception ex ) { if( Misc.IsCriticalException( ex ) ) throw; // ignore exceptions for now since we've no way to let clients add exception handlers } } _fBusy = false; } } private void PreWinEventProc(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime) { // Ignore events from the UIA->MSAA bridge: these are recognizable as having // >0 idObject, and the target HWND having a UIA impl. if (idObject > 0) { if (UiaCoreApi.UiaHasServerSideProvider(hwnd)) { // Bridge event - ignore it. return; } } // 0 is used as a marker value elsewhere, so bump up to 1 if(eventTime == 0) { eventTime = 1; } WinEventProc(eventId, hwnd, idObject, idChild, eventTime); } private void Init() { // Keep the garbage collector from moving things around _winEventProc = new NativeMethods.WinEventProcDef(WinEventReentrancyFilter); _gchThis = GCHandle.Alloc(_winEventProc); _clientCallbacks = new ArrayList(2); _qEvents = new Queue(16, (float)2.0); // (initial cap, growth factor) _fFlags = NativeMethods.WINEVENT_OUTOFCONTEXT; } #endregion Private Methods //----------------------------------------------------- // // Private Fields // //------------------------------------------------------ #region Private Fields private class WinEvent { internal WinEvent(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime) { _eventId = eventId; _hwnd = hwnd; _idObject = idObject; _idChild = idChild; _eventTime = eventTime; } public int _eventId; public IntPtr _hwnd; public int _idObject; public int _idChild; public uint _eventTime; } private Queue _qEvents; // Queue of events waiting to be processed private int [] _eventIds; // the WinEvent(s) this instance is handling private IntPtr [] _hHooks; // the returned handles(s) from SetWinEventHook private bool _fBusy; // Flag indicating if we're busy processing private int _fFlags; // SetWinEventHook flags private GCHandle _gchThis; // GCHandle to keep GCs from moving this callback private NativeMethods.WinEventProcDef _winEventProc; // the callback handed to USER for WinEvents protected ArrayList _clientCallbacks; // the client callback interface objects #endregion Private Fields } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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